Refactoring Massive App Delegate using Composite pattern. See blog post for more details: https://www.vadimbulavin.com/refactoring-massive-app-delegate

RefactoringAppDelegate-Composite.swift

enum AppDelegateFactory {
    static func makeDefault() -> AppDelegateType {
        return CompositeAppDelegate(appDelegates: [PushNotificationsAppDelegate(), StartupConfiguratorAppDelegate(), ThirdPartiesConfiguratorAppDelegate()])
    }
}

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?
    let appDelegate = AppDelegateFactory.makeDefault()

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        _ = appDelegate.application?(application, didFinishLaunchingWithOptions: launchOptions)
        return true
    }

    func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
        appDelegate.application?(application, didRegisterForRemoteNotificationsWithDeviceToken: deviceToken)
    }
}